Two anti-internment posters printed in the 1970s. The Civil Authorities (Special Powers) Act (Northern Ireland) 1922 enabled ‘internment’; the arrest without warrant and detention without trial those suspected of belonging to an illegal paramilitary group.

In 1971, the Prime Minister of Northern Ireland, Brian Faulkner, the chief constable and general officer commanding (GOC) agreed to introduce interment for those suspected of being involved in violence. The names of 450 alleged terrorists were collated using Royal Ulster Constabulary (RUC) Special Branch intelligence. Although the UVF and other Loyalist paramilitaries were active, only those considered Republican were targeted. The list was inaccurate and out of date. Many of the accused were members of the Official Irish Republican Army (Official IRA), an organisation that had been largely inactive for many years. The names of people with no paramilitary association, such as members of Northern Ireland Civil Rights Association, were also included.

On the 9 August, police and soldiers arrested 342 men. The Nationalist community were incensed by the one-sided application of internment and later by the interrogation techniques used on prisoners. Hostility towards the security forces grew and violence erupted across Belfast. The day after internment was introduced, 10 people were killed in the city and during the following weeks, thousands of people were displaced from their homes. The operation was deemed a failure because it did not target any of the leading Provisional IRA members and led to an upsurge in violence in the province. In the aftermath, there was an increase in the frequency and seriousness of attacks on the RUC which left seven officers dead.